U.S. patent number 7,115,154 [Application Number 10/459,785] was granted by the patent office on 2006-10-03 for process for purifying hydrogen streams using composite adsorbents.
This patent grant is currently assigned to UOP LLC. Invention is credited to Vladislav I. Kanazirev.
United States Patent |
7,115,154 |
Kanazirev |
October 3, 2006 |
Process for purifying hydrogen streams using composite
adsorbents
Abstract
A process for purifying various hydrocarbon streams using a
composite adsorbent is disclosed. The adsorbent contains a zeolite,
an alumina and a metal component. The metal component (M.sub.add)
is present in an amount (over and above the amount of exchangeable
M metal in the zeolite) at least 10 mole % the stoichiometric
amount of metal (M) (expressed as the oxide) needed to balance the
negative charge of the zeolite lattice. In a specific application
an adsorbent comprising zeolite X, alumina and sodium is used to
purify an ethylene stream in order to remove CO.sub.2, H.sub.2S,
methanol, and other S- and O-containing compounds from the
stream.
Inventors: |
Kanazirev; Vladislav I.
(Arlington Heights, IL) |
Assignee: |
UOP LLC (Des Plaines,
IL)
|
Family
ID: |
33491041 |
Appl.
No.: |
10/459,785 |
Filed: |
June 12, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
09733693 |
Dec 8, 2000 |
6632766 |
|
|
|
Current U.S.
Class: |
95/135;
210/690 |
Current CPC
Class: |
B01J
20/3483 (20130101); B01J 20/30 (20130101); B01J
20/3408 (20130101); B01J 20/28019 (20130101); B01J
20/3007 (20130101); B01J 20/08 (20130101); C10L
3/12 (20130101); B01J 20/3078 (20130101); B01J
20/041 (20130101); B01J 20/3035 (20130101); C10G
70/047 (20130101); B01J 20/3085 (20130101); B01D
15/00 (20130101); B01J 20/183 (20130101); B01J
20/3491 (20130101); C07C 7/13 (20130101); B01J
20/28042 (20130101); B01J 20/18 (20130101); Y02C
20/40 (20200801); B01J 2220/42 (20130101); Y02C
10/08 (20130101) |
Current International
Class: |
B01D
53/02 (20060101) |
Field of
Search: |
;210/660,689,690
;95/90,116,141,117,128,133,134,135,138,139,140 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Johnson; Jonthan
Attorney, Agent or Firm: Tolomei; John G. Molinaro; Frank
S.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of application Ser. No.
09/733,693 filed 8 Dec. 2000 now U.S. Pat. No. 6,632,766, the
contents of which are hereby incorporated by reference in their
entirety.
Claims
What is claimed is:
1. A process for removing contaminants from hydrocarbon streams
comprising contacting the stream with a solid shaped adsorbent, at
adsorption conditions to remove at least a portion of at least one
contaminant, the adsorbent comprising an alumina component, a
zeolite component and a metal component (M.sub.add), the metal
component present in an amount from about 0.015 to about 0.08 moles
of M.sub.add, expressed as the oxide, per 100 g of adsorbent.
2. The process of claim 1 where the hydrocarbon stream is an olefin
stream.
3. The process of claim 1 where the adsorption conditions include a
temperature of about ambient to about 80.degree. C. and a pressure
of about atmospheric to about 100 atm.
4. The process of claim 1 where the hydrocarbon stream is a liquid
stream and is contacted with the adsorbent at a LHSV of about 0.5
to about 10 hr.sup.-1.
5. The process of claim 1 where the hydrocarbon stream is a gaseous
stream and is contacted with the adsorbent at a GHSV of about 500
to about 10,000 hr-1.
6. The process of claim 1 where the contaminants comprise at least
one of CO.sub.2, H.sub.2S, COS, O.sub.2 and CO.
7. The process of claim 1 where the zeolite is selected from the
group consisting of zeolite X, zeolite Y, zeolite A and mixtures
thereof.
8. The process of claim 1 where the metal component (M.sub.add) is
an alkali metal selected from the group consisting of sodium,
potassium, lithium, rubidium, cesium and mixtures thereof.
9. The process of claim 1 where the zeolite is present in an amount
from about 5 to about 55 wt. % of the adsorbent.
Description
FIELD OF THE INVENTION
This application relates to a process for removing contaminants
from hydrocarbon streams, e.g. removing CO.sub.2, COS, H.sub.2S,
AsH.sub.3, methanol, mercaptans and other S- or O-containing
organic compounds from ethylene, propylene, C.sub.3 C.sub.4
hydrocarbon products and other light hydrocarbon streams. The
process involves contacting the stream with an adsorbent which
comprises a zeolite, an alumina component and a metal component
e.g. sodium, in an amount at least 10% of the zeolite's ion
exchange capacity.
BACKGROUND OF THE INVENTION
Solid adsorbents are commonly used to remove contaminants from
hydrocarbon streams such as olefins, natural gas and light
hydrocarbon fractions. Since these streams can contain different
contaminants, more than one adsorbent or adsorbent bed are needed
to sufficiently purify the stream so that it can be used in the
desired process. Contaminants which can be present in these streams
include H.sub.2O, CO, O.sub.2, CO.sub.2, COS, H.sub.2S, NH.sub.3,
AsH.sub.3, PH.sub.3, Hg, methanol, mercaptans and other S- or
O-containing organic compounds.
However, while various adsorbents can remove one or more
contaminant, they can also remove and/or promote reactions of the
desired hydrocarbon. For example, faujasite type zeolites, e.g.
zeolite 13X, are good adsorbents for sulfur and oxygenate compounds
but they are also good adsorbents for olefins which results in high
temperature rise that can cause run-away reactions. Additionally,
owing to the zeolite's residual surface reactivity reactions such
as oligomerization and polymerization can occur during
regeneration. This leads to fouling and performance
deterioration.
In attempts to remedy this problem, there are reports in the art
where zeolites have been mixed with alumina. U.S. Pat. No.
4,762,537 discloses the use of an adsorbent comprising zeolite Y
and alumina to remove HCl from a hydrogen stream. In U.S. Pat. No.
4,686,198 and U.S. Pat. No. 4,717,483 it is disclosed that a
mixture of alumina and sodium Y zeolite can remove ammonia sulfides
and organic impurities from waste water. The sodium Y zeolite
contains at least 12.7 wt. % Na.sub.2O. The same adsorbent is also
used to reduce the acidity and moisture content of used
organophosphate functional fluids, see U.S. Pat. No. 4,751,211. The
use of alumina with alkali or alkaline earth metal for removing HCl
and other contaminants is disclosed in U.S. Pat. No. 6,013,600.
Applicant has developed an improved adsorbent which can remove
multiple contaminants from various hydrocarbon streams.
Surprisingly these contaminants can be removed with only a small
temperature rise and the adsorbent has increased stability upon
multiple regenerations. This adsorbent comprises a zeolite, alumina
and a metal component (M.sub.add) which is present in an amount
(over and above the M metal present in the zeolite) of at least 10
mole % of the stoichiometric amount of metal (expressed as the
oxide) needed to compensate for the negative charge of the zeolite
lattice.
SUMMARY OF THE INVENTION
This invention relates to a process for removing contaminants from
a hydrocarbon stream using a solid shaped adsorbent. Accordingly,
one embodiment of the invention is a process for removing
contaminants from hydrocarbon streams comprising contacting the
stream with a solid shaped adsorbent, at adsorption conditions to
remove at least a portion of at least one contaminant, the
adsorbent comprising an alumina component, a zeolite component and
a metal component (M.sub.add), the metal component present in an
amount (over and above the amount of exchangeable M metal in the
zeolite) at least 10 mole % of the stoichiometric amount of metal
(M), expressed as the oxide, needed to compensate for the negative
lattice charge of the zeolite.
These and other objects and embodiments will become clearer after a
detailed description of the invention.
DETAILED DESCRIPTION OF THE INVENTION
Applicant's invention comprises a purification process using a
solid shaped adsorbent. With regard to the solid shaped adsorbent,
one necessary component is an activated alumina. Activated aluminas
include aluminas having a surface area usually greater than 100
m.sup.2/g and typically in the range of 100 to 400 m.sup.2/g.
Further, the activated alumina powder is preferably obtained by
rapid dehydration of aluminum hydroxides, e.g., alumina trihydrate
in a stream of hot gasses or solid heat carrier. Dehydration may be
accomplished in any suitable apparatus using the stream of hot
gases or solid heat carrier. Generally, the time for heating or
contacting with the hot gases is a very short period of time,
typically from a fraction of a second to 4 or 5 seconds. Normally,
the temperature of the gases varies between 400.degree. and
1000.degree. C. The process is commonly referred to as flash
calcination and is disclosed, for example in U.S. Pat. No.
2,915,365, incorporated herein by reference. However, other methods
of calcination may be employed.
The activated aluminas suitable for use in the present invention
have a median particle size in the range of 0.1 to 300 microns,
preferably 1 to 100 microns and typically 1 to 20 microns. In
certain instances, it may be desirable to use aluminas with a
median particle size of 1 to 10 microns. The alumina may be ground
to the desired particle size before or after activation. The
activated alumina typically has an LOI (loss on ignition) in the
range of about 5 to 12% at a temperature of 200.degree. to
1000.degree. C.
One source of activated alumina is gibbsite which is one form of
alumina hydrate derived from bauxite using the Bayer process.
However, alpha alumina monohydrate, pseudoboehmite or the alumina
trihydrate may be used if sufficiently calcined. Other sources of
alumina may also be utilized including clays and alumina
alkoxides.
Another necessary component of the present invention is a zeolite.
Zeolites are crystalline aluminosilicate compositions which are
microporous and which have a three-dimensional oxide framework
formed from corner sharing AlO.sub.2 and SiO.sub.2 tetrahedra.
Zeolites are characterized by having pore openings of uniform
dimensions, having a significant ion exchange capacity, and being
capable of reversibly desorbing an adsorbed phase which is
dispersed throughout the internal voids of the crystal without
significantly displacing any atoms which make up the permanent
zeolite crystal structure. The zeolites which can be used in the
present invention are those which have a pore opening of about 5 to
about 10 .ANG..
In general, the zeolites have a composition represented by the
empirical formula: M.sub.2/nO:Al.sub.2O.sub.3:bSiO.sub.2 M is a
cation having a valence of "n" and "b" has a value of about 2 to
about 500. Preferred zeolites are those that have a
SiO.sub.2/Al.sub.2O.sub.3 ratio of about 2:1 to about 6:1 and/or
those having the crystal structure of zeolite X, faujasite, zeolite
Y, zeolite A, mordenite, beta and ferrierite. Especially preferred
zeolites are zeolites X, Y and A.
Preparation of these zeolites is well known in the art and involves
forming a reaction mixture composed of reactive sources of the
components which mixture is then hydrothermally reacted to form the
zeolite. Specifically, the synthesis of zeolite Y is described in
U.S. Pat. Nos. 3,130,007 and 4,503,023 and that of zeolite X in
U.S. Pat. Nos. 2,883,244 and 3,862,900, the disclosures of which
are incorporated by reference.
Although the synthesis of zeolites, and zeolites X and Y in
particular, are well known, a brief description will be presented
here for completeness. Reactive sources of M include without
limitation the halide and hydroxide compounds of alkali or alkaline
earth metals such as sodium chloride, sodium hydroxide, potassium
hydroxide, etc. Aluminum sources include but are not limited to
boehmite alumina, gamma alumina and soluble aluminates such as
sodium aluminate or tetraethylammonium aluminates. Finally, silicon
sources include, without limitation, silica, silica hydrosol,
silicic acid, etc.
The reactive sources are combined into a reaction mixture which has
a composition in terms of mole ratios of the oxides of:
.times..times..times..times..times. ##EQU00001## and the mixture is
then reacted to form the zeolite.
As synthesized, the zeolites will contain "M" metals in the
channels and/or pores. The function of these metal cations is to
balance the negative charge of the zeolite lattice. Since these
cations are not part of the framework, they are exchangeable and
are said to occupy exchange sites. The total amount of metal
cations present in the zeolite is referred to as the stoichiometric
amount or the maximum ion exchange capacity of the zeolite. This
amount is usually expressed in moles.
Since the metal cations initially present in the zeolite are
exchangeable they can be exchanged for other (different) alkali
metals, alkaline earth metals, hydrogen ions, ammonium ions or
mixtures thereof. If the zeolite to be used contains partially or
completely hydrogen or ammonium ions, then these ions must be fully
exchanged with alkali metals, alkaline earth metals or mixtures
thereof, either before or during the preparation of the composite
adsorbent.
Another necessary component of the shaped adsorbent of this
invention is a metal component (M.sub.add) selected from the group
consisting of alkali, alkaline earth metals and mixtures thereof.
This metal component (M.sub.add) is in addition to the metal cation
(M) present in the exchange sites of the zeolite. That is, the
M.sub.add is present over and above the amount of exchangeable M
metal ion present in the exchange sites of the zeolite.
Additionally the M.sub.add metal can be the same or different than
the M metal. For example, the M metal in a zeolite can be potassium
whereas the M.sub.add can be sodium.
Specific examples of M.sub.add include but are not limited to
sodium, potassium, lithium, rubidium, cesium, calcium, strontium,
magnesium, barium, zinc and copper. The source of the (metal
component precursor) can be any compound which at activation
conditions, (see infra) decomposes to the metal oxide. Examples of
these sources are the nitrates, hydroxides, carboxylates,
carbonates and oxides of the metals. The shaped adsorbent can be
prepared by combining the three components in any order and forming
into a shaped article although not necessarily with equivalent
results.
In one method, the alumina, zeolite and an aqueous solution of the
desired metal compound are mixed and formed into a shaped article.
For example, gamma alumina, zeolite X and a solution of sodium
acetate can be combined into a dough and then extruded or formed
into shapes such as pellets, pills, tablets or spheres (e.g. by the
oil drop method) by means well known in the art. A preferred method
of forming substantially rounded shapes or bodies involves the use
of a pan nodulizer. This technique uses a rotating pan or pan
nodulizer onto which is fed the alumina component, zeolite
component and a solution of the metal component thereby forming
substantially rounded articles or bodies.
Another method of forming the shaped article is to mix powders of
the alumina, zeolite and metal compound followed by formation of
pellets, pills, etc. A third method is to combine the alumina and
zeolite components (powders), form them into a shaped article and
then impregnate the shaped article with an aqueous solution of the
metal compound. The forming step is carried out by any of the means
enumerated above.
In preparing a solution of the desired metal compound, it is
preferred to adjust the pH to a value from about 7 to about 14,
more preferably from about 12 to about 14 and most preferably from
about 12.7 to about 13.8. The pH of the solution is controlled by
adding the appropriate amount of the desired metal hydroxide. For
example, if sodium is the desired metal, sodium acetate can be used
to form the aqueous solution and the pH is then adjusted using
sodium hydroxide.
Having obtained the shaped articles, they are cured or dried at
ambient temperature up to about 200.degree. C. for a time of about
5 minutes to about 25 hours. The shaped articles can be cured in
batches e.g. bins or trays or in a continuous process using a
moving belt. Once the shaped articles are cured, they are activated
by heating the cured articles at a temperature of about 275.degree.
C. to about 600.degree. C. for a time of about 5 to about 70
minutes. The heating can be done with the articles in a moving pan
or in a moving belt where the articles are direct fired to provide
the finished solid adsorbent.
The relative amount of the three components can vary considerably
over a wide range. Usually the amount of alumina varies from about
40 to about 90% of the adsorbent and the amount of zeolite varies
from about 5 to about 55 wt. % of the adsorbent. The amount of
metal component, M.sub.add, can also vary considerably, but must be
present in an amount equal to at least 10% of the stoichiometric
amount of the metal cation, M, present in the exchange sites of the
zeolite. For practical reasons, the maximum amount of M.sub.add
should be no more than 50% of the stoichiometric amount of M. In
absolute terms, it is preferred that the amount of M.sub.add be
present from about 0.015 to about 0.08 moles of M.sub.add per 100
gm of adsorbent. The amounts of M and M.sub.add are reported or
expressed as the oxide of the metal, e.g. Na.sub.2O.
The finished adsorbent can now be used to remove contaminants from
various hydrocarbon streams. The streams which can be treated
include but are not limited to hydrocarbon streams, especially
those containing saturated and/or unsaturated hydrocarbons. Olefin
stream such as ethylene, propylene and butylenes can be especially
treated using the instant adsorbent. These streams will contain one
or more of the following contaminants: H.sub.2O, CO, O.sub.2,
CO.sub.2, COS, H.sub.2S, NH.sub.3, AsH.sub.3, PH.sub.3, Hg,
methanol, mercaptans and other S- or O-containing organic
compounds.
The hydrocarbon streams are purified by contacting the stream with
the solid adsorbent at adsorption conditions. The contacting can be
carried out in a batch or continuous process with continuous being
preferred. The adsorbent can be present as a fixed bed, moving bed
or radial flow bed with fixed bed being preferred. When a fixed bed
is used, the feed stream can be flowed in an upflow or downflow
direction, with upflow being generally preferred for liquid feeds.
If a moving bed is used the feed stream flow can be either
co-current or counter-current. Further, when a fixed bed is used,
multiple beds can be used and can be placed in one or more reactor
vessel. Adsorption conditions include a temperature of about
ambient to about 80.degree. C., a pressure of about atmospheric to
about 100 atm. (1.01.times.10.sup.4 kPa) and a contact time which
depends on whether the hydrocarbon stream is a liquid or gaseous
stream. For a liquid stream the contact time expressed in terms of
liquid hourly space velocity (LHSV) is from about 0.5 to about 10
hr.sup.-1, while for a gaseous stream, the gas hourly space
velocity varies from about 500 to about 10,000 hr.sup.-1.
After a certain amount of time, which time depends on the
concentration of contaminants, the size of the bed and the space
velocity, the adsorbent will be substantially spent, i.e. has
adsorbed an amount of contaminant(s) such that the level of
contaminant in the purified stream is above an acceptable level. At
this time, the adsorbent is removed and replaced with fresh
adsorbent. The spent adsorbent can be regenerated by means well
known in the art and then placed back on service. In a typical
regeneration procedure, the adsorbent is first drained and
depressurized followed by a cold purge with an inert stream. Next,
a warm purge in a downflow direction at 80 150.degree. C. removes
the retained hydrocarbons from the bed. Finally, the temperature is
slowly raised to 280 320.degree. C. and held there for at least 2
hours and then cooled to ambient temperature.
The following examples are set forth in order to more fully
illustrate the invention. It is to be understood that the examples
are only by way of illustration and are not intended as an undue
limitation on the broad scope of the invention as set forth in the
appended claims.
EXAMPLE 1
Balls containing alumina, zeolite 13X and sodium where prepared as
follows. A rotating pan device was used to continuously form beads
by simultaneously adding activated alumina powder (AP) and zeolite
13X powder (Z) while spraying the powders with a sodium acetate
solution (NaAc). The mass ratio (on a volatile free basis) was 1.0
AP:0.23 Z:0.04 NaAc. Water was added as needed to keep the sodium
acetate dissolved and to provide for sufficient agglomeration. The
pH of the NaAc solution was adjusted to 13.3 by adding a NaOH
solution. The balls, which had a size distribution from 1.2 to 4 mm
were cured at 60 80.degree. C. for three hours using a heated belt.
Finally, the cured beads were activated in an oven at about
450.degree. C. for one hour. The amount of each component (wt. %)
on a volatile free basis was found to be 78.7% AP; 18.1% Z; 3.2%
Na.sub.2O.
EXAMPLE 2
The procedure set forth in Example 1 was used to prepare balls
except that the mass ratio of AP:Z:NaAc was 1.0:0.55:0.035. The
amount of each component (wt. %) on a volatile free basis was found
to be 63.1% AP; 34.7% Z; 2.2% Na.sub.2O.
EXAMPLE 3
The procedure set forth in Example 1 was used to prepare balls
except the mass ratio of AP:Z:NaAc was 1.0:0.37:0.05. The amount of
each component (wt. %) on a volatile free basis was found to be
70.4% AP; 26.1% Z; 3.5% Na.sub.2O.
EXAMPLE 4
The procedure in Example 3 was used to prepare balls except that
water was used instead of NaAc. The amount of each component (wt.
%) on a volatile free basis was found to be 72.9% AP; 26.9% Z; 0.2%
Na.sub.2O.
EXAMPLE 5
The process of Example 1 was carried out except that zeolite NaY
(obtained from UOP LLC) was used instead of zeolite 13.times. and
the ratio was 1AP:0.37Z. The amount of each component (wt. %) on a
volatile free basis was found to be 72.9% AP; 26.9% Z; 0.2%
Na.sub.2O.
EXAMPLE 6
In a rotating container there were placed 500 g of the balls from
Example 5 and 200 g of a 4.6 wt. % sodium acetate solution. The
balls were cured by rotating the closed container for one hour and
then activated as per Example 1. The amount of each component (wt.
%) on a volatile free basis was found to be 72.36% AP; 26.7% Z;
0.94% Na.sub.2O.
EXAMPLE 7
Balls were prepared as in Example 6 except that a solution
containing 10.9 wt. % sodium acetate was used. The amount of each
component (wt. %) on a volatile free basis was found to be 71.65%
AP; 26.44 Z; 1.91% Na.sub.2O.
EXAMPLE 8
Balls were prepared as in Example 6 except that a solution
containing 17.1% sodium acetate was used. The amount of each
component (wt. %) on a volatile free basis was found to be 70.9%
AP; 26.18% Z; 2.88% Na.sub.2O.
EXAMPLE 9
Samples from Examples 1 7 were tested for CO.sub.2 and propylene
adsorption using a McBain balance. CO.sub.2 is used to measure
adsorption of acidic gases, while propylene measures the ability to
adsorb organic compounds. About 30 mg of each sample was heated in
flowing helium to 400.degree. C. at a rate of 25.degree. C./min.
held there for about 45 min. and then cooled (under helium to room
temperature). Adsorption was carried out by flowing a stream of
either 1% propylene in helium or 1.5% CO.sub.2 in helium over the
sample at 38.degree. C. for 20 minutes and measuring the weight
change. The results are presented in Table 1.
TABLE-US-00001 TABLE 1 Adsorption Capacity* of Various Adsorbents
Na.sub.2O Na.sub.2O mol/100/gm mol/100 gm Sample ID total added
Propylene CO.sub.2 Example 1 0.108 0.052 2.57 3.9 Example 2 0.147
0.035 4.06 4.8 Example 3 0.140 0.056 3.22 4.3 Example 4 0.089
0.003*** 3.3 3.5 Example 5 0.058 none 2.37 0.78** Example 6 0.071
0.012 2.29 0.85** Example 7 0.087 0.028 2.2 0.99** Example 8 0.103
0.044 2.22 1.1* *Capacity in g adsorbate/100 g adsorbent
**pre-treatment temperature 232.degree. C. ***added as NaOH to
adjust the pH during preparation
Examples 1 4 used zeolite X while Examples 5 8 used zeolite Y. For
both zeolites it is observed that the propylene adsorption is
affected very little by the addition of sodium, but the CO.sub.2
adsorption improves considerably.
EXAMPLE 10
Samples from Examples 1 4 were tested for surface reactivity using
1-hexene as the probe molecule. About 70 mg from each sample (as a
powder) was placed in a tubular flow reactor placed in a furnace.
Each sample was activated at 350.degree. C. for 1 hour in helium
and then cooled to 150.degree. C. Next a feed stream prepared by
bubbling helium through a saturator containing 1-hexene was flowed
through the catalyst at a rate of 20 cc/min, while measuring the
hexene conversion at various temperatures in the temperature range
of 150.degree. C. to 500.degree. C. Hexene conversion was measured
using a gas chromatograph. The major product of this reaction at
low conversion were 2-hexene and 3-hexene. Formation of methyl
branched isomers and cracking products occurred at high conversion.
The overall conversion of 1-hexene are shown in Table 2.
TABLE-US-00002 TABLE 2 1-hexene Conversion (%) of Various
Adsorbents Sample ID 200.degree. C. 250.degree. C. 350.degree. C.
Example 1 0 0 7.4 Example 2 0 0 15.5 Example 3 0 0 7.5 Example 4
18.8 57.8 83.4
This data clearly shows that an alumina/zeolite adsorbent without
additional sodium (Example 4) has much more reactivity for 1-hexene
conversion. Since the adsorbents are regenerated in the same
temperature range as the range in Table 2, the low catalytic
activity of the adsorbents of Examples 1 3 indicates that the
presence of sodium (at the above levels) would strongly reduce the
likelihood of coking or run-away reaction when the above adsorbents
undergo regeneration.
Samples from Example 5 8 were tested as above and the results are
presented in Table 3.
TABLE-US-00003 TABLE 3 1-hexene Conversion (%) of Various
Adsorbents Sample ID 200.degree. C. 250.degree. C. 300.degree. C.
Example 5 45.2 79.4 89 Example 6 5.9 38.5 71.3 Example 7 0.7 6.4
24.5 Example 8 0.2 -- 10.8
The results in Table 3 show the same performance using zeolite Y as
shown in Table 2 using zeolite X. That is the presence of
additional sodium greatly reduces the reactivity of the
adsorbent.
EXAMPLE 11
A series of zeolites were combined with alumina (AP) and sodium
acetate powders and thoroughly mixed. A small sample was
transferred to a microbalance, activated in a helium flow at
700.degree. C. and then cooled to 38.degree. C. Propylene
adsorption measurements were carried out as per Example 9 and the
results presented in Table 4.
TABLE-US-00004 TABLE 4 Effect of Components of Propylene Adsorption
Propylene Composition (wt. %) Adsorption Sample ID AP NaY 13X 3A
Na.sub.2O (g/100 g) A 72.7 27.3 3.29 B 69.7 26.2 4.1 2.66 C 25.4
70.6 4.0 1.33 D 77.1 22.9 2.42 E 74.7 22.2 3.2 2.12 F 21.2 74.6 4.2
0.84
The results in Table 4 show that the addition of sodium does not
affect propylene adsorption very much (compare samples A vs. B and
D vs. E). However, when the adsorbent contains only zeolites,
additional sodium lowers propylene adsorption (samples A vs. C and
D vs. F). This shows the function of the alumina.
* * * * *